<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>add and sub</title>
</head>
<body>
    <div id="app">
        <div class="input-num">
            <button @click="sub">-</button>
            <span>{{ num }}</span>
            <button @click="add">+</button>
        </div>
        <img src="http://www.itheima.com/images/logo.png" alt="">
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
        var app = new Vue({
            el:"#app",
            data:{
                num:1
            },
            methods:{
                add:function(){
                    if(this.num<10){
                        this.num++;
                    }else{
                        alert("别点了，最大只能是10!")
                    }
                },
                sub:function(){
                    if(this.num>0){
                        this.num--;
                    }else{
                        alert("别点了，最小只能是0！")
                    }
                }
            }
        })
    </script>
</body>
</html>